Legend of Heroes: Trails into Reverie - Reminiscence: Buried Trails, Beaten Trails, Blazed Trails

The title barely fits, but this is one of the stories from the Slab of Reminiscence. It shows us how Rixia met Swin and Nadia, and it even has an optional fight. I was a little concerned at first that it was going to be like Anelace from Sky 3 (light on details here due to spoilers) where the battle would be fairly difficult or luck based, but luckily you have all of the tools you need and it seems Rixia isn't actively looking to kill them. Once things are smoothed over, the assassins go their separate ways and we are left to wonder what story will we find next.

That and Rixia's dancer outfit as a reward...